Process for the purification of synthetic methyl alcohol



Patented Jan. 21, 1930 UNITED STATES) PATENT, orrlcs EDUARD 'rscnumzun AND ALBERT xmntnorn, or coLoeNn-mULnEm, omen,

ASSIGNORS "1:0 I. o. rmnnmnusrnm AKTIENGESELLSCHAFT, or rnanxro'n'r ON-THE-MAIN, GERMANY, A CORPORATION or GERMANY r raoonss non THE PURIFICATION or SYNTHETIC METHYL ALCOHOL- No Drawing. Application filed ember 12,1927, {Serial No. 225,838, and in Germany outlier-27,

The present invention concerns a process for the purification of synthetic methyl alcohol by which the synthetic methyl alcohol produced or individual fractions obtained by the distillation thereof, are subjected to a treatment with permanganate, if desired fol:-

lowed by the addition of organic bases and zinc chloride.

Synthetic methyl alcohol obtained. 1 from oxides of carbon and hydrogen occasionally possesses apeculiar unpleasant odor, due to the presence of small quantities of various 1 impurities. This odor is different from that v of methyl alcohol (wood spirit) obtained by the carbonizationof wood. These impurities usually interfere with the purification of synthetic methyl alcohol and individual fractions thereof obtained by distillation to such an extent, that the customary methods of purification used forwood spirit, such for exam 1e, as fractional distillation by means of a ractionatingcolumn, are generally not by themselves, sufficient to produce methyl alcohol of a high degree of purity as regards boiling point, stab1lity to permanganate, odor, etc.

According to the present invention this y, disadvantage of synthetic methyl alcohol is eliminated by subjecting the crude synthetic methyl alcohol or individual, distillation fractions thereof to a treatment with permanganate either before, during or. after the fractionaldistillation thereof. The amounts of permanganate necessary for this purification are very small. Accordingly it is not neces sary to use permanganate in a quantity sufficient. to destroy all the impurities. as are oxidizable' at ordinary temperature, anaddition of 0.1 to 0.3 percent of permanganate calculated on the crude methyl alcohol suffices,

for example to improve the quality of the same to a very marked'extent." The process is extremely simple. The requisite quantity of potassium permanganate is dissolved in water and crude methyl alcohol or individual fractions thereof from the distillation of the same are gradually added to thissolution with stirringat ordinary temperature. The purification process commences'immediately.

With methyl alcohol considered particularand in distillingthe methyl cohol is gradually added hour) at ordinary temperature in a vessel pro- 1y impure is advantageous to add.to the methyl alcohol or the individual distillation fractions thereof after the previous treatment with permanganate, small quantities (about 0.3- to 0.5 per cent calculated on the methyl 1 alcohol used) of such an organic base asis not volatile with methyl'alcohol'vapors, such for example, as phenylene 'diamine, toluylene diamine, amino phenols, phenyl hydrazine and the like.- These bases act as condensing agents at elevated temperatures on various impurities. contained in the methyl alcohol, alcohol, these impurities remain behind.

The following example will serve to illustrate our invention:

EwampZe.-To 20,000 kgs, of methyl al- I vided with stirrer a solution of 30 kgs. of

during about one potassium permanganate in water with stirrlng. The mixture is then fractionated in p known manner in a fractionating column of customary construction with or without the a'ddltion of water and organic bases.

As already stated the crude methyl alcohol mentioned, ammonia or organic bases it is purified from the same by treatment with zinc chloride or solutions of zinc chloride subsequently to the treatment wi permanganate and then distilled. W

In this manner methyl alcohol is obtained .which is completely free from ammonia and organic bases. The amountof zinc chloride necessary for the purification naturally depends on the ammonia content ofthe methyl alcohol. Part of the calculated amount of zinc chloride may be'replaced by anequivalent quantity of hydrochloric acid, withthe same result.

We claim:

1. In the plrocess for the purification of synthetic met yl alcohol thestep which coma treatment wit 2. In the processfor the purification of v ment with permanganate, and then with a prises 'subjectin synthetic methyl alcohol to permanganate.

synthetic methyl alcohol the step which comprises subjecting synthetic methyl alcohol to a treatment with permanganate and then adding an organic base which is not volatile with the alcoholic vapors.

3. In the process for the purification of synthetic methyl alcohol the step which comprises subjecting synthetic methyl alcohol to a treatment with permanganate and zinc chloride;

4. In the process for the purification of synthetic methyl alcohol the step which comprises subjecting methyl alcohol to a treatsolution of zinc chloride.

In testimony whereof we have hereunto set our hands.

EDUARD TSCHUNKUR.

ALBERT KLAMROTH. 

